1 Traditional Computing
- As computing matures, the lines among many of the traditional computing environments are blurring.
- Just a few years ago, this environment consisted of PCs connected to a network, with servers providing file and print service
- Terminals attached to mainframes were prevalent at many companies as well, with even fewer remote access and portability options.
- The current trend is toward more ways to access these environments.
- Web technologies are stretching the boundaries of traditional computing.
- Companies implement portals which provide web accessibility to their internal servers.
- At home, most users had a single computer with a slow modem connection to the office, the Internet, or both. Network connection speeds once attainable only at great cost are now available at low cost, allowing more access to more data at a company or from the Web.
- Those fast data connections are allowing home computers to serve up web pages and to contain their own networks with printers, client PCs, and servers.
- Some homes even have firewalls to protect these home environments from security breaches.
- Those firewalls cost thousands of dollars a few years ago, and did not even exist a decade ago.
2 Web-Based Computing
- The Web has become ubiquitous, leading to more access by a wider variety of devices than was dreamt about a few years ago.
- Web computing has increased the emphasis on networking.
- Devices that were not previously networked now have wired or wireless access.
- Devices that were networked now have faster network connectivity, either by improved
- networking technology, optimized network implementation code, or both.
- The implementation of web-based computing has given rise to new categories of devices, such as load balancers which distribute network connections among a pool of similar servers.
- Generally, the Web has increased the complexity of devices as their users require them to be web-enabled.
3 Embedded Computing :-
- Embedded computers are the most prevalent form of computers in existence.
- They run embedded real-time operating systems. These devices are found everywhere, from car engines and manufacturing robots to VCRs and microwave ovens. They tend to have very specific tasks.
- The systems they run on are usually primitive, lacking advanced features, such as virtual memory, and even disks. Thus, the operating systems provide limited features.
- They usually have little or no user interface, preferring to spend their time monitoring and managing hardware devices, such as automobile engines and robotic
- Some are general-purpose computers, running standard operating systems such as UNIX-with special-purpose applications loaded to implement the functionality.
- Others are hardware devices with a special-purpose operating system embedded within, providing just the functionality desired.
- The use of embedded systems continues to expand.
- The power of those devices, both as standalone units and as members of networks and the Web, is sure to increase as well.
Operating-System Services :-
Operating System provides an environment for the execution of program. It provides certain services to program & to the user of that program. To make that task of programming easier. They are as follow:
- Program Execution:-
In Program Execution system must be load into memory & run that programs.
The program must be able to end its execution either normally or abnormally.
- Input/output Operation: –
Since the running program may require input/output which may involve a file or an input/output device cannot be directly control by the user.
The operating system must provide the means to the input/output operations.
- File System manipulation: –
The program needs to create, delete & access the file.
Also it is used to create & delete them by name, searching for a given file and list file information.
In many cases one process needs exchange information with other process.
On the same or different machine. The operation system should support some mechanism for interposes communication.
- Error Detection: –
The operating system takes appropriate action for various types of error.
To ensure correct & consisting computing errors occurs in CPU & memory hardware, in input/output devices & user program.
- Resource Allocation: –
When multiple user or jobs are running at the same time resources must be allocated to each of them.
There are many types of resources which are managed by the operating system.
This service is used to keep track on how and what kind of resources are been used by the user.
The statistic calculated is useful for the researchers for reconfiguring or improving the system.
- Protection and Security:-
This service is particularly useful to owner who wanted to keep control to access of the information on the multi-user system